// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.

using System.IO;
using System.Linq;
using SixLabors.ImageSharp.Formats.Jpeg;
using SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder;
using SixLabors.ImageSharp.IO;
using SixLabors.ImageSharp.Metadata;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
using Xunit;
using Xunit.Abstractions;

namespace SixLabors.ImageSharp.Tests.Formats.Jpg
{
    [Trait("Format", "Jpg")]
    public class SpectralToPixelConversionTests
    {
        public static readonly string[] BaselineTestJpegs =
            {
                TestImages.Jpeg.Baseline.Calliphora, TestImages.Jpeg.Baseline.Cmyk, TestImages.Jpeg.Baseline.Jpeg400,
                TestImages.Jpeg.Baseline.Jpeg444, TestImages.Jpeg.Baseline.Testorig420,
                TestImages.Jpeg.Baseline.Jpeg420Small, TestImages.Jpeg.Baseline.Bad.BadEOF,
                TestImages.Jpeg.Baseline.MultiScanBaselineCMYK
            };

        public SpectralToPixelConversionTests(ITestOutputHelper output)
        {
            this.Output = output;
        }

        private ITestOutputHelper Output { get; }

        [Theory]
        [WithFileCollection(nameof(BaselineTestJpegs), PixelTypes.Rgba32)]
        public void Decoder_PixelBufferComparison<TPixel>(TestImageProvider<TPixel> provider)
            where TPixel : unmanaged, IPixel<TPixel>
        {
            // Stream
            byte[] sourceBytes = TestFile.Create(provider.SourceFileOrDescription).Bytes;
            using var ms = new MemoryStream(sourceBytes);
            using var bufferedStream = new BufferedReadStream(Configuration.Default, ms);

            // Decoding
            using var converter = new SpectralConverter<TPixel>(Configuration.Default, cancellationToken: default);
            var decoder = new JpegDecoderCore(Configuration.Default, new JpegDecoder());
            var scanDecoder = new HuffmanScanDecoder(bufferedStream, converter, cancellationToken: default);
            decoder.ParseStream(bufferedStream, scanDecoder, cancellationToken: default);

            // Test metadata
            provider.Utility.TestGroupName = nameof(JpegDecoderTests);
            provider.Utility.TestName = JpegDecoderTests.DecodeBaselineJpegOutputName;

            // Comparison
            using (Image<TPixel> image = new Image<TPixel>(Configuration.Default, converter.GetPixelBuffer(), new ImageMetadata()))
            using (Image<TPixel> referenceImage = provider.GetReferenceOutputImage<TPixel>(appendPixelTypeToFileName: false))
            {
                ImageSimilarityReport report = ImageComparer.Exact.CompareImagesOrFrames(referenceImage, image);

                this.Output.WriteLine($"*** {provider.SourceFileOrDescription} ***");
                this.Output.WriteLine($"Difference: {report.DifferencePercentageString}");

                // ReSharper disable once PossibleInvalidOperationException
                Assert.True(report.TotalNormalizedDifference.Value < 0.005f);
            }
        }
    }
}